Relative Performance of Root and Shoot Development in Enset and East African Highland Bananas

RELATIVE PERFORMANCE OF ROOT AND SHOOT DEVELOPMENT IN ENSET AND EAST AFRICAN HIGHLAND BANANAS

G. BLOMME, G. SEBUWUFU 1, TEMESGEN ADDIS2 and L. F. TURYAGYENDA Bioversity Uganda, P. O. Box 24384, Kampala, Uganda 1Crop Science Department, Makerere University P. O.Box 7062, Kampala, Uganda 2Southern Agricultural Research Institute (SARI), Awassa Research Center, P. O. Box 06, Awassa, Ethiopia

ABSTRACT

East African highland bananas and enset belong to the genera Musa and Ensete (Ensete ventricosum), respectively. The root, corm and shoot growth of field-established enset and East African highland banana cultivars was assessed. Banana and wild enset plants were assessed in Uganda, while domesticated enset plants were assessed in Ethiopia. Growth traits of the enset and banana mats in Uganda were recorded at flower emergence of the banana plant crop, while enset plants in Ethiopia were assessed at 4 and 5 years after planting. The results obtained in Uganda indicate that enset had a significantly (P<0.05) shorter and thicker pseudostem compared to banana. In addition, enset had a larger root system with thicker cord roots. Results further showed that young enset plants had a significantly lower shoot-root ratio compared to the bananas. The shoot-root ratio in enset is, however, clone dependent and increases with an increase in age. The results also showed that root density in enset sharply decreases with increasing soil depth.

Key Words: Ensete ventricosum, Ethiopia, shoot-root ratio, Uganda

RÉSUMÉ

Les bananas de montagne d’Afrique de l’Est appartiennent respectivement à l’espèce genera Musa, et Ensete (Ensete ventricosum), La croissance des racines, bulbes et rejetons de champ-établi d’enset et de cultivars de banane de montagne d’Afrique de l’Est, ont été évaluée. La banane et les plantes d’enset sauvages ont été évaluées en Ouganda, pendant que les plantes d’enset domestiqué ont été évaluées en Ethiopie. Les traits de croissance des tapis d’enset et banane en Ouganda ont été enregistrés à l’apparition de fleur de la récolte de plante de banane, pendant que les plantes d’enset en Ethiopie ont été évaluées à 4 et 5 ans après la plantation Les résultats obtenus en Ouganda indiquent que cet enset a eu significativement (P<0.05) pseudostem plus court et plus épais à comparer à la banane. Par ailleurs, enset a un plus grand système fondamental avec les racines de corde plus épaisses. Les résultats poussés ont montré que ces jeunes plantes d’enset ont une grande proportion des rejetons en comparaison avec celle des bananes. La proportion des rejetons de enset est cependant un clone dépendant des augmentations de l’âge. Les résultats ont montré aussi que la densité des racines de enset diminue avec l’augmentation de la profondeur du sol.

Mots Clés: Ensete ventricosum, Ethiopie, la proportion tire-fondamental, Ouganda

INTRODUCTION Ethiopia where products processed from the corm and the pseudostem are a major source of food The Musaceae family is subdivided into the for more than 12 million people (Barker and genera Musa and Ensete (Simmonds, 1966). While Simmonds, 1953; Bezuneh and Feleke, 1966; the banana fruit is known worldwide, enset Westphal, 1975; CSA, 1997). Whereas the banana (Ensete ventricosum) is only cultivated in fruit is harvested within a relatively short period 52 G. BLOMME et al. of less than 2 years after planting (YAP), enset is better understand plant stability across the usually harvested at the end of the vegetative Musaceae family. This research could hence stage between 5-7 YAP. The time to flower contribute to future banana and enset breeding emergence in enset depends on climatic work focussing on plant stability, shoot-root ratio conditions, genotype and management level and even research on plant response to nematode (Brandt et al., 1997). Enset corms and and weevil infestation. pseudostems are normally processed at 5-7 YAP. The production of both banana and enset is MATERIALS AND METHODS constrained by a number of factors including pests and diseases, and reduced soil fertility. Wild Ugandan enset plants (Photo 1) and East Enset, being monocarpic and thus unbranched, African highland bananas (cultivars ‘Siira’ and has proven to be firmly anchored in the soil and ‘Entaragaza’) (Musa AAA-EA group) were toppling of field-grown pre-flowering plants is a planted and assessed at the Makerere University rare occurrence (Price, 1995). In contrast, banana Agricultural Research Institute, Kabanyolo whose lateral shoots are expected to add to the (MUARIK) located in Central Uganda (0o 28’ N, plants’ stability, is more susceptible to toppling. 32o37’E, 1,150 m above sea level). The site has a The aim of this study was to compare; root, corm mean annual rainfall of 1,300 mm, which is bi- and shoot growth of field-established enset and modally distributed. The soils are classified as East African highland bananas, and to get insight Eutric ferralsols according to the USDA (Yost and into the shoot-root ratio of banana and enset to Estwaran, 1996). The trial site had been under a

Photo 1. A 16 months old wild enset plant assessed in Uganda. Root and shoot development in enset and East African highland bananas 53 grass fallow for a period of 5 years and was Furadan was applied on the soil around the mat manually prepared in order to avoid soil at planting and at 14 WAP. No irrigation was disturbance. carried out. Seeds of wild enset plants were collected from In addition, two clones of domesticated enset a swampy area 30 km north of Kampala in Uganda. (‘Yeka’ and ‘Masha Gamo’) were assessed at the The seeds were soil planted. Subsequently, the Southern Agricultural Research Institute (SARI) young wild enset plants were raised in a nursery research station in Awassa, southern Ethiopia (70 for 8 weeks before field establishment. The field 03’N, 380 30’E, 1,700 m above sea level). The site layout was a randomised complete block design has a mean annual rainfall of 1,046 mm, which is and plant spacing was 4 m x 4 m. The banana and bi-modally distributed. The soils are classified as enset plants were planted in holes 60 cm wide Eutric nitosols according to the USDA (Ethiopian and 60 cm deep. Mapping Authority, 1988; Yost and Estwaran, For the East African highland bananas, two 1996). types of banana planting materials were used: One year old plants of both enset clones were pared suckers and in vitro plantlets. Six plants field established. Five plants per clone were per banana genotype and planting material type assessed at 4 YAP, while an additional 2 plants were used, while 14 enset plants were assessed. per clone were assessed at flower emergence [5 To control nematodes and weevils, 20 g of YAP] (Photo 2). In Ethiopia, the enset plants were

Photo 2. A flowering 5 year old ‘Mashagamo’ enset plant assessed in Ethiopia. 54 G. BLOMME et al. planted in holes with a diameter and depth of 30 showed that the corms of enset plants had a similar cm, at a spacing of 2 m between rows and 1.5 m weight with the banana corms (Table 1). However, between plants in a row. enset plants had a significantly lower shoot-root Pesticides and chemical fertilisers were not dry weight ratio than the bananas (Table 1). The applied. However, a single application of 0.5 kg lower shoot-root ratio probably indicates that composted manure was applied per plant at three young enset plants partition more assimilates months after planting. The plants were not towards root growth compared to bananas. This irrigated. Regular weeding was carried out and may be one of the reasons why enset has old enset leaves were regularly pruned. enhanced plant stability. In addition, the thick In Uganda, growth traits of the wild enset cord roots of the enset plants may enhance the plants and banana mats (i.e. mother plant and plant’s tolerance to nematodes and may enhance lateral shoots) were recorded at flower emergence the plants anchorage strength. of the banana crop (i.e. 1.3 YAP), while 4 and 5 The number of cord roots for the in vitro- year old domesticated enset plants were assessed derived Entaragaza plants and enset did not differ in Ethiopia. significantly (Table 1). The number of banana Data were taken on shoot and root growth. roots varies considerably depending upon the The shoot parameters measured included plant health status of the plant. A healthy corm of a height (PH), circumference of the pseudostem at mature plant can bear 200 to 300 primary cord soil level (PC) and leaf area (LA). Leaf length and roots with a total length of 230 m (Robin and leaf widest width were measured and LA was Champion, 1962; Beugnon and Champion, 1966). calculated according to Obiefuna and Ndubizu However, a banana mat (i.e. mother plant and (1979). Leaf dry weight (LW) and pseudostem lateral shoots) at flowering of the mother plant dry weight (PSW) were also recorded. can have over 600 cord roots (Blomme, 2000). The plants were completely excavated and During the final stages of vegetative growth, the following corm and root data was collected: the enset root system size stagnates or even corm dry weight (CW) number of adventitious or decreases (Table 2). This may be partially linked cord roots (NR), cord root length (LR), average to the observed ‘high mat’ phenomenon, whereby diameter at the base of the cord roots (AD) and the corm and newly formed roots progressively root dry weight (RW). Cord root length was grow above soil level. There is a clear increase in measured using the line intersect method the enset shoot-root ratio with increasing age (Tennant, 1975), while the diameter of the cord (Tables 1 and 2). This is in agreement with roots was measured with a Vernier Caliper. The observations made for banana (Blomme, 2000). shoot-root ratio was calculated as the ratio of The enset shoot-root ratio also depends on the leaf, pseudostem and corm dry weight over root clone (Table 2). This is in contrast to observations dry weight. In addition, root distribution down made by Blomme (2000) on banana where similar the soil profile was also assessed on one 4 year shoot-root ratios were observed for the mats of old Yeka’ and one 4 year old ‘Masha Gamo’ enset several genotypes. plant in Ethiopia. Data were subjected to analysis The root distribution down the soil profile using the Microsoft Excel and SAS (SAS, 1999) assessed on 4- year old domesticated enset computer packages. plants showed that the root density decreases with increasing soil depth (Fig. 1). About 89 and RESULTS AND DISCUSSION 96% of cord roots of, respectively, ‘Yeka’ and ‘Mashagamo’ plants were found within the upper The results obtained in Uganda indicate that at 40 cm soil layer. Similarly, enset root system 1.3 YAP enset had invested more in leaf biomass assessment conducted at Yirgachefe in southern and had a significantly (P<0.05) shorter and Ethiopia (6012’N, 38012’E, 1,847 m above sea level) thicker pseudostem compared to bananas (Table on 2 year old ‘Genticha’ plants showed that 96% 1). In addition, enset had a larger root system of the cord roots were found within the upper 40 with thicker cord roots (Table 1). Results further cm soil layer (Addis, 2005). Root and shoot development in enset and East African highland bananas 55

a b b a

12.8a 130.5a 130.5a 136.0a 136.0a ratio ratio 10.87 32.89 37.87 2.50a 1 3.33a 3.17a

22.60 a b

b a 0.64 1.10 15.4ba 15.4ba 9.8bc 9.8bc 18.9ba 18.9ba 20.3a 3.17a 76.7a 20.3a 3.17a 3.7c 0 0 3.7c 0 S-R ratio NS HTS 0.80 0.80

a b b a

3982b 3370b 4391b 6024b 20167a 357.77 361.57 224.86 762.4a 354.28

b a a b -derived plants; SD: sucker-derived plant; NA: not 502.20 505.00 269.33 419.80 i.e. 5 years after planting) in Ethiopia diameter at the base of cord roots (cm); NR: number in-vitro

a b a b ); LFW: leaf fresh weight (g); LDW: leaf dry weight (g); PSFW: ); LFW: leaf fresh weight (g); LDW: dry PSFW: ring stage ( 2 ding to Tukey’s studentised range test; YAP: Years after planting; Years YAP: studentised range test; Tukey’s ding to 364.0c 3908.3b 394.7b 394.7b 364.0c 3908.3b 608.2ba 4516.7b 4516.7b 608.2ba 456.2b 624.7a 3308.3b 334.1b 334.1b 3308.3b 624.7a 622.0a 3168.3b 320.0b 320.0b 3168.3b 622.0a 417.5bc 7548.1a 1.01 0.46 1.26 0.62

a b a b 0.60b 0.58b 0.54b 0.55b 1.15a 3.25 5.40 8.06 7.81

a b 999.6ba 1300.8a 1300.8a

1279.8ba 919.4b 919.4b a b 5.91 7.50 15.44 12.06 5975ba 7775a 6850ba 1146.0ba 6850ba 1146.0ba 7650ba 5495b

a b a b ); LW: Leaf dry weight (kg); PSW: Pseudostem dry weight (kg); CW: Corm dry weight (kg); RW: Root Corm dry weight (kg); RW: Pseudostem dry weight (kg); CW: Leaf dry weight (kg); PSW: ); LW: 2 1.63 2.17 4.19 3.39 PSDW PSDW CW 2914.5a CDW AD NR RFW RDW RL 3207.0a 2349.0ba

a b b

a 1.83 1.46 2.50 36863a

1.73 a b

a b 124.8b 33500a 1.73 1.58 1.27

1.26

a b

a b 4216.7b 1 4041.7b 1078.1b 20198bc 1757.3bc 1757.3bc 20198bc 1078.1b 4041.7b 4065.0b 1084.3b 3905.0b 1041.7b 27000ba 3905.0b 1041.7b 7606.1a 2028.9a 14386c 1251.6c 2028.9a 7606.1a 2.09 2.24 and enset mother plants grown in Uganda measured at flower emergence of the banana plant crop (1.3 years after planting) Musa Mashagamo Clone Clone PH PC LA LW PSW CW RW NR RL S-R AD 55.0b 15.3b 4.42a 55.0b 15.3b 49.7b 12.3b 5.72a 49.7b 12.3b 46.3b 13.5b 4.89a 46.3b 13.5b 47.3b 12.0b 4.59a 47.3b 12.0b 90.7a 21.7a NA NA 90.7a 21.7a 76.9c 5 5 Yeka 1.69 mber of plants

# assessed assessed 4 YAP Genotype PH PC NL LA LFW LDW PSW PSW LDW LFW LA NL TABLE 1. Plant growth traits of PC PH Genotype Entaragaza (IV) 212.5a Means in a column followed by the same letter are not significantly different at p<0.05 according to Tukey’s studentised range test; IV: TABLE 2. Mean values for shoot and root traits of domesticated enset plants assessed at 4 years after planting flowe Plant age Nu Entaragaza (SD) 208.7a Siira (IV) 182.2b Siira (SD) 191.8ba assessed; PH: plant height (cm); PC: pseudostem circumference at soil level NL: number of leaves; LA: leaf area (m enset enset dry weight (kg); NR: Number of cord roots; RL: Cord root length (m); AD: Average diameter at the base of the cord roots (cm); S-R ratio: Ratio of leaf, pseudostem and corm dry weight over ratio: Ratio of leaf, pseudostem and corm dry weight over diameter at the base of cord roots (cm); S-R Average AD: dry weight (kg); NR: Number of cord roots; RL: Cord root length (m); root dry weight pseudostem fresh weight (g); PSDW: pseudostem dry weight (g); CFW: corm fresh weight (g); CDW: corm dry weight (g); AD: average corm dry weight (g); corm fresh weight (g); CDW: pseudostem dry weight (g); CFW: pseudostem fresh weight (g); PSDW: of cord roots; RFW: root fresh weight (g); RDW: dry RL: length (cm); S-R ratio: ratio leaf, pseudostem and corm dry weight over root weight; NS: number of suckers, HTS: height of the tallest sucker (cm) 4 YAP 5 YAP 5 at p<0.05 accor Means in a column (analysis was done per age group) followed by the same letter are not significantly different 2 Yeka PH: Plant height (m); PC: Pseudostem circumference at soil level LA: Leaf area (m 5 YAP 2 Mashagamo 2.87 56 G. BLOMME et al.

45 Yeka 40 Masha gamo

15 % of total number of cord roots cord of number total % of 10

0 0 -10 10-- 20 20 - 30 30 - 40 40 - 50 50 - 60 60 - 70 70 - 80 80 -90 90 -100 Depth [cm]

Figure 1. Distribution of enset roots down the soil profile for 4 year old plants of the clones ‘Yeka’ and ‘Mashagamo’ assessed in Ethiopia.

ACKNOWLEDGEMENTS under field conditions and the influence of different biophysical factors on this Financial support from Bioversity International, relationship. Ph.D. thesis N° 421. K.U.Leuven. the Rockefeller foundation and the Flemish Faculty of Agriculture and Applied Biological Association for Development Cooperation and Sciences. Belgium. pp. 183. Technical Assistance (V.V.O.B., Belgium) is Brandt, S. A., Anita, S., Clifton, H., Terrence, M.C. gratefully acknowledged. J., Endale, T., Mulugeta, D., Gizachew, W. M, Gebre Y., Masyoshi, S. and Shiferaw, T. 1997. REFERENCES The “Tree against Hunger”: Enset- based agricultural systems in Ethiopia. American Addis, T. 2005. Biology of enset root mealybug Association for the Advancement of Science, (Cataenococcus ensete) Williams and Matile- Washington, DC, USA. pp. 56. Ferrero (Homoptera: Pseudococcidae) and its CSA, (Central Statistical Authority), 1997. Area, geographical distribution in southern production and yield of crops of private Ethiopia. M. Sc. Thesis. Alemaya University, holdings in 1996/97 in Meher season. Addis Ethiopia. pp. 81. Ababa, Ethiopia. Barker, R.E.D. and Simmonds, N.W. 1953. The Ethiopian Mapping Authority. 1988. National genus Enset in Africa. Kew Bulletin 3:405- Atlas of Ethiopia. Addis Ababa, Ethiopia. pp. 416. 76. Beugnon, M. and Champion, J. 1966. Etude sur Obiefuna, J.C. and Ndubizu, T.O.C. 1979. les racines du bananier. Fruits 21: 309-327. Estimating leaf area of plantain. Scientia Bezuneh, T. and Feleke, A. 1966. The production Horticulturae 11: 31-36. and utilization of the genus enset in Ethiopia. Price, N.S. 1995. Banana morphology, part 1: roots Economic botany 20:65-70. and rhizomes. In: S. Gowen (Ed.), pp.190-205. Blomme, G. 2000. The interdependence of root Bananas and Plantains, Chapman and Hall. and shoot development in banana (Musa spp.) Root and shoot development in enset and East African highland bananas 57 Robin, J. and Champion, J. 1962. Etudes des Westphal, E. 1975. Agricultural system in émissions des racines de la variété du Ethiopia, Center for Agricultural Publishing bananier Poyo. Fruits 17: 93-94. and Documentation, Wageningen. pp 14. SAS institute. 1999. SAS Institute Release 8.2 Inc., Yost, D., and H. Estwaran. 1996. Major Land Cary, NC, USA. Resource Areas of Uganda. World Soil Simmonds, N.W. 1966. Bananas. 2nd ed. Resources, Soil Conservation Service, USDA, Longman, London and New York. Washington D.C. Tennant, D. 1975. A test of a modified line intersect method for estimating root length. Journal of Ecology 63: 995-1001.